Abstract.
We present range-Doppler images of the Moon using 6 meter wavelength, which have been obtained using the Jicamarca Radio Observatory 49.92 MHz radar. The observations were performed using circular polarization on transmit and two orthogonal linear polarizations on receive, allowing scattering images to be obtained with the polarization matched to the transmitted wave (polarized), and at a polarization orthogonal to the transmitted wave (depolarized). The images have approximately 10 km resolution in range 20 km resolution in Doppler, allowing many large scale features, including maria, terrae, and impact craters to be identified. The long wavelength penetrates efficiently into the subsurface of the Moon, allowing radar images to be used for studies of subsurface composition. Strong depolarized return due to resonant scatter is observed from relatively new impact craters with large breccia and shallow regolith. Terrae regions with less lossy surface material also appear bright in both depolarized and polarized images. Mare regions are characterized by lower polarized and depolarized return, indicating that composition of the surface is more lossy. We also report low polarized and depolarized backscatter two notable regions on the Moon that have the optical appearance of Terrae composition: 1) the Schiller-Zucchius impact basin in the Southern hemisphere, and 2) The region between Mare Frigoris and Mare Imbrium. Low radar return indicates that the subsurface of these regions is lossy. We present a comparison of radar observations in these regions with surface FeO and TiO_2 content to help pinpoint the features responsible for radar loss.